There are many applications for polymers having either organic or inorganic fillers within the polymeric matrix to provide a desired property or properties. One such application is in the nuclear field where various fillers, such as lead, cadmium or boron may be used as fillers in a polymeric matrix for nuclear or reactor shielding. These composites may possess the desirable nuclear shielding properties of the filler and the desirable mechanical properties of the polymeric matrix. It is sometims desirable to recover the filler from filled polymer surplus, scrap or waste. This is particularly true in the case of boron since it is relatively expensive.
Previous methods for recovering boron filler from a polymer matrix have various disadvantages. One approach is to disintegrate minced or ground boron-filled polymer with organic solvents, but this has the disadvantage of there not being inexpensive, effective solvents for some organic binder materials. Another approach is to heat the organic material in an air or oxygen atmosphere until the organic binder reacts. This approach has the disadvantage that an objectionable portion of the boron is oxidized during the reaction and may be lost if other recovery steps are not performed. A third approach is to heat the organic material in an inert atmosphere until it decomposes and to sunsequently extract the elemental boron from the resulting organic char by reacting it with a halogen, distilling off volatile boron halide and then reconverting the halide to elemental boron. This approach has the disadvantage of several relatively costly processing steps.